Analytical modelling of wintertime coastal jets in the Adriatic Sea

Two diagnostic models, reproducing circulation generated in a marginal sea by variable density, have been developed. The models’ domain is a 2D transverse section for which analytical solutions have been obtained. They describe the winter situation in the northern Adriatic, with a strong vertical mixing present and the density maximum dominating the centre of the basin. Both models employ Boussinesq-type parametrisation of friction and linear slip at the bottom. The first model allows for frictional departure from hydrostatic equilibrium and includes vertical friction only. The second one is hydrostatic but allows for lateral friction as well. The results obtained by the two models are similar and to some extent dependent on the vertical and bottom friction. They reproduce several well known characteristics of the Adriatic circulation (cyclonic surface flow, downwelling in the central and larger part of the basin compensated by upwelling in the coastal zone) but also predict some phenomena that are still not well understood. A conspicuous feature of the model results are coastal jets, which were observed in the Adriatic on several occasions. The present models show that the distance of jets from the coasts depends on lateral friction: it is found to vary from 1 up to 10 km on the Italian side and between 2 and 15 km on the Croatian side. Both models reproduce the west–east asymmetry, with the wider current on the east side of the basin. The asymmetry is a subject on which conflicting empirical results exist in the Adriatic. In the two models cyclonic flow occupies the whole water column, which disagrees with some recent theoretical findings of the near-bottom anticyclonic flow and thus leaves the issue open.     

Photoelectric analysis of asteroid 216 Kleopatra: Implications for its shape

In some recent theoretical papers it has been suggested that gravitationally bound “rubble piles” in hydrostatic equilibrium possibly exist among the asteroids. For a higher-than-critical value of the angular momentum acquired by such a body, the instability phenomena can produce fission into a binary system. S. J. Weidenschilling [Icarus44, 807–809 (1980)] suggested that 216 Kleopatra may represent a binary asteroid, since it has a large light curve amplitude (1.3–1.4 mag). In this paper new observations of Kleopatra are presented, suggesting the equal plausibility of the single triaxial ellipsoid model. Namely, when phase and aspect effects are taken into account, the actual maximum amplitude is reduced to about 0.9 mag at 90° of aspect which is close to the value predicted by theory for the instability limit. Moreover, multiple-scattering effects [M. Poutanen, E. Bowell, and K. Lumme, Bull. Amer. Astron. Soc.13, 725 (1981)] can reduce the axial ratio a/b even more. If the single-body model is adopted, the density of Kleopatra should be on the order of 1.7 g/cm³. This low value seems reasonable for “rubble pile” models.     

Cooling Radius vs. Absorption Size of Galaxies

The discussion of the relationship between cooling radius in two-phaseadiabatic halo models and observationally established maximal radiusof absorption in luminous galaxies at low redshift is presented. It isof paramount importance that any viable model of the halo is able toreproduce empirical value of the absorption cross-section of normalgalaxies and its scaling with luminosity. Several ways for bringingthe theoretical and observational values into agreement are outlined.It is of great methodological importance to fully assess the difficultiesany model is likely to encounter when testing predicted extent ofabsorption and column density distribution against recently obtainedlow-redshift Ly absorption data.     

Enhancing a GIS Cellular Automata Model of Land Use Change: Bayesian Networks, Influence Diagrams and Causality

Cellular Automata (CA) models at present do not adequately take into account the relationship and interactions between variables. However, land use change is influenced by multiple variables and their relationships. The objective of this study is to develop a novel CA model within a geographic information system (GIS) that consists of Bayesian Network (BN) and Influence Diagram (ID) sub‐models. Further, the proposed model is intended to simplify the definition of parameter values, transition rules and model structure. Multiple GIS layers provide inputs and the CA defines the transition rules by running the two sub‐models. In the BN sub‐model, land use drivers are encoded with conditional probabilities extracted from historical data to represent inter‐dependencies between the drivers. Using the ID sub‐model, the decision of changing from one land use state to another is made based on utility theory. The model was applied to simulate future land use changes in the Greater Vancouver Regional District (GVRD), Canada from 2001 to 2031. The results indicate that the model is able to detect spatio‐temporal drivers and generate various scenarios of land use change making it a useful tool for exploring complex planning scenarios.     

Adsorptive removal of eight heavy metals from aqueous solution by unmodified and modified agricultural waste: tangerine peel

Analysis was carried out using tangerine peel aiming its use as a potential adsorbent of eight heavy metal ions (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) from aqueous solution. This agricultural waste was tested both in its untreated and also chemically modified form. Based on Fourier transformation infrared spectra, a comparison of biosorbent structure before and after chemical treatment was made. Batch adsorption tests were conducted at different pH and mass of sorbent to examine the influence on the effectiveness of simultaneous removal of tested ions. Kinetic studies were conducted at optimum pH 5.0 and sorbent dosage 300 mg. The pseudo-second-order kinetic model best fit the experimental data with high correlation coefficients (r² > 0.9997). By optimizing listed parameters, high removal efficiencies (> 89%) were achieved. According to the results obtained in this study, the remediation of water polluted with heavy metals could be done using modified tangerine peel as an agricultural waste material.     

Factors triggering landslide occurrence on the Zemun loess plateau,Belgrade area,Serbia

Among the numerous factors that trigger landslide events, the anthropogenic impact caused by inadequate planning and faulty land use in urban areas is increasing. The Zemun settlement on the northern outskirts of Belgrade has experienced a number of landslides in the last three decades, endangering buildings and roads, and claiming human lives, particularly in the case of the 2010/2011 landslides. Selected meteorological parameters were used to calculate rainfall erosivity indices such as Precipitation Concentration Index and Modified Fournier Index over the period 1991–2015. Drought indices, Lang aridity index and Palfai Drought Index were calculated as well. Mann–Kendall trend test was applied to identify potential rising and/or declining trends both in meteorological parameters and calculated indices. Trend analysis of the annual and seasonal scales yielded a statistically significant trend in the spring time series. Stable arid and pronounced drought conditions were recorded. The modified Fournier index based on monthly mean values yields moderate aggressiveness, with several extreme values indicating very high erosivity classes, especially for 2010/2011. The geological substrate is predominantly loess and hence highly susceptible to erosion and slope failure when climatological conditions are suitable. Accelerated urbanization at the end of the last century reduced vegetation cover, intensified pressure on the vertical loess slope, and lacked suitable rain drainage systems so that surface-water runoff was directed into the porous loess, thereby endangering slope stability. We proposed a geomorphic model to describe the nature of the erosional processes on the loess cliffs of the Zemun loess plateau. Results from this study have implications for mitigation strategies.     

Importance of the unsaturated zone in landslide reactivation on flysch slopes: observations from Valići Landslide,Croatia

Landslides - Field investigations and back-analyses of (re)activated landslides in the Rje?ina River Valley indicate prolonged intense rainfall and the rise of the groundwater table, often to...     

Malaco temperature reconstructions and numerical simulation of environmental conditions in the southeastern Carpathian Basin during the Last Glacial Maximum

We investigate the glacial climate conditions in the southeastern Carpathian Basin (Vojvodina, Serbia) based on the reconstruction of malacological palaeotemperatures and results from a high-resolution regional climate simulation. Land snail assemblages from eight loess profiles are used to reconstruct July temperatures during the Last Glacial Maximum (LGM). The malacological reconstructed temperatures are in good agreement with the simulated LGM July temperatures by the Weather Research and Forecast model. Both methods indicate increasing temperatures from the northwestern towards the southeastern parts of the study area. LGM aridity indices calculated based on the regional climate model data suggest more arid conditions in the southeastern parts compared with more humid conditions in the northwestern parts. However, for present-day conditions, the moisture gradient is reversed, exhibiting more humid (arid) conditions in the southeast (northwest). An explanation for the reversed LGM aridity pattern is provided by an analysis of the prevailing wind directions over the South Banat district (Serbia). The prevailing moist northwesterly winds during summer are not able to compensate for the annual lack of moisture induced by the dry winds from the southeast that are more frequent during the LGM for the other seasons.     

Re-analysis of late Quaternary dust mass accumulation rates in Serbia using new luminescence chronology for loess–palaeosol sequence at Surduk

Despite numerous palaeoenvironmental investigations of loess–palaeosol sequences across the Carpathian Basin, well-dated high-resolution records are scarce. This paper presents a new high-resolution chronology for the loess-palaeosol sequence at Surduk (Serbia), based on optically stimulated luminescence (quartz) and post-infrared infrared stimulated luminescence (polymineral) dating. The presented record spans 53–19 ka, with primary loess deposition occurring after 52±2 ka, and differs from previously published chronologies that relied on less precise and now superseded dating protocols. Based on the new chronology, mass accumulation rates (MARs) for Surduk were constructed and compared with sites in the Carpathian Basin. The results demonstrate that accumulation periods across this area are not consistent in timing or rates. The high-resolution dating strategy identifies a disturbance in sediment deposition that occurred after 45±2 ka and implies that site contains a hiatus. Finally, we show samples that failed routine dose recovery and preheat plateau tests, and had low fast ratios. Supported by bulk sample geochemical analysis it is proposed that a potential abrupt source shift, during the Last Glacial Maximum, may be the cause of the anomalous luminescence behaviour.